U.S. patent number 7,119,140 [Application Number 10/898,084] was granted by the patent office on 2006-10-10 for transparent films, compositions, and method of manufacture thereof.
Invention is credited to Ronald Basham, Gheorghe Cojocariu, Robert R. Gallucci, Anshu S. Ghosal, Emine Elif Gurel, Grant Hay.
United States Patent |
7,119,140 |
Basham , et al. |
October 10, 2006 |
Transparent films, compositions, and method of manufacture
thereof
Abstract
A film comprising in admixture a thermoplastic resin component
comprising a thermoplastic resin component and a glass having a
refractive index within 0.04 of the thermoplastic resin component,
wherein the film has a haze of less than about 20%, total
transmittance of greater than about 70%, and a coefficient of
thermal expansion of about 20 to about 80 um/m/.degree. C. measured
over a temperature range of 20 to 70.degree. C. The films are of
particular utility in optical applications such as light diffuser
films.
Inventors: |
Basham; Ronald (Evansville,
IN), Cojocariu; Gheorghe (Evansville, IN), Gallucci;
Robert R. (Mt. Vernon, IN), Ghosal; Anshu S. (New Delhi,
110017, IN), Gurel; Emine Elif (Evansville, IN),
Hay; Grant (Evansville, IN) |
Family
ID: |
35005826 |
Appl.
No.: |
10/898,084 |
Filed: |
July 22, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20060020075 A1 |
Jan 26, 2006 |
|
Current U.S.
Class: |
524/494 |
Current CPC
Class: |
C08J
5/18 (20130101); G02B 5/0247 (20130101); G02B
5/0268 (20130101); G02B 5/0278 (20130101); G02B
6/0051 (20130101); C08J 2369/00 (20130101) |
Current International
Class: |
B60C
1/00 (20060101); C08K 3/40 (20060101) |
Field of
Search: |
;524/494 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
40 16 417 |
|
Nov 1991 |
|
DE |
|
0 138 528 |
|
Oct 1984 |
|
EP |
|
0 248 308 |
|
Dec 1987 |
|
EP |
|
0 254 054 |
|
Jan 1988 |
|
EP |
|
0 376 052 |
|
Jul 1990 |
|
EP |
|
0 387 570 |
|
Sep 1990 |
|
EP |
|
0 434 848 |
|
Jul 1991 |
|
EP |
|
0 500 325 |
|
Feb 1992 |
|
EP |
|
0 524 731 |
|
Jun 1992 |
|
EP |
|
0 517 927 |
|
Dec 1992 |
|
EP |
|
0 522 753 |
|
Jan 1993 |
|
EP |
|
0 567 655 |
|
Nov 1993 |
|
EP |
|
0 628 600 |
|
Dec 1994 |
|
EP |
|
0 645 422 |
|
Mar 1995 |
|
EP |
|
1 553 138 |
|
Sep 2002 |
|
EP |
|
1 561 732 |
|
Oct 2003 |
|
EP |
|
WO 02/38675 |
|
May 2002 |
|
WO |
|
WO 2004/035497 |
|
Apr 2004 |
|
WO |
|
Other References
JP 04-225062 Aug. 14, 1992 (translation of abstract only). cited by
other .
JP 04-249537 Sep. 4, 1992 (translation of abstract only). cited by
other .
JP 05-156170 Jun. 22, 1993 (translation of abstract only). cited by
other .
JP 05-255583 Oct. 5, 1993 (translation of abstract only). cited by
other .
JP 05-311075 Nov. 22, 1993 (translation of abstract only). cited by
other .
JP 06-184424 Jul. 5, 1994 (translation of abstract only). cited by
other .
JP 06-212070 Aug. 2, 1994 (translation of abstract only). cited by
other .
JP 06-228424 Aug. 16, 1994 (translation of abstract only). cited by
other .
JP 09-040856 Feb. 10, 1997 (translation of abstract only). cited by
other .
Nakao, T., et al. "High Performance Plastic Substrate for Flat
Panel Displays" The 10th International Display Workshop, Fukuoka,
Japan (Dec. 3-5, 2003) 621-624. cited by other .
Okamaoto, Masaya "Relationship between the Composition of
Polycarbonate Copolymers and the Refractive Index", Journal of
Applied Polymer Science, vol. 84, 514-521 (2002). cited by other
.
DE 40 16 417A1; Nov. 28, 1991 (translation of abstract only). cited
by other .
EP 0 248 308; Dec. 9, 1987 (translation of abstract only). cited by
other .
EP 0 387 570; Sep. 19, 1990 (translation of abstract only). cited
by other .
JP05294671. Publication Date Nov. 9, 1993. Glass Fiber for
Reinforcing Polycarbonate Resin. (Abstract Only). cited by other
.
JP04008761. Publication Date Jan. 13, 1992. Polycarbonate Resin
Composition. (Abstract Only). cited by other .
JP58060641. Publication Date Apr. 11, 1983. Glass Fiber Composition
(Abstract Only). cited by other .
JP05155638. Publication Date Jun. 22, 1993. Glass Composition.
(Abstract Only). cited by other .
JP2000063653. Publication Date: Feb. 29, 2000. Polycarbonate Resin
Composition Having Transparency and Slidabiliity. (Abstract Only).
cited by other .
International Search Report for International Application No.
PCT/US2005/025964. Date Mailed: Oct. 20, 2005. cited by
other.
|
Primary Examiner: Nutter; Nathan M.
Claims
The invention claimed is:
1. A film comprising in admixture: a thermoplastic resin component
comprising a polycarbonate; and a glass having a refractive index
within 0.04 of the thermoplastic resin component, wherein the glass
is essentially free of compounds selected from the group consisting
of aluminum oxides, boron oxides, boric acids and a combination
comprising at least one of the foregoing; wherein the glass has
been passivated with a passivating agent containing a silicon
hydride functionality, wherein the passivating agent is of the
formula (10) or (11); ##STR00009## wherein m is greater than or
equal to 1; the sum of m and n is equal to 1 to 10,000; m+p is 3 to
about 1,000; R.sup.g and R.sup.i are each independently hydrogen,
alkyl, aryl, alkylaryl, alkoxy, aryloxy, haloakyl, haloaryl, and
haloalkylaryl; R.sup.j and R.sup.k are each independently alkyl,
aryl, alkylaryl, alkoxy, aryloxy, haloalkyl, haloaryl, and
haloalkylaryl; and R.sup.h is trialkylsilyl, arylalkysilyl,
triarylsilyl, hydrogen, alkyl, aryl, alkylaryl, haloalkyl,
haloaryl, or haloalkylaryl; wherein the passivating agent is
present at about 0.001 to about 1.0 wt. % of the film; wherein the
film has a thickness of about 0.01 to about 3.0 mm; and wherein the
film composition has a haze of less than about 20%, a total
transmittance of greater than about 70%, and a coefficient of
thermal expansion of about 20 to about 70 um/m/.degree. C. measured
over a temperature range of 20 to 70.degree. C.
2. The film of claim 1 wherein the polycarbonate composition has a
yellowness index of less than about 10.
3. The film of claim 1 with a flexural modulus of at least about
2500 MPa.
4. The film of claim 1 wherein the glass contains greater than
about 10 wt. % zirconia.
5. The film of claim 1 where the glass is an alkali resistant
glass, a dense barium crown glass, an electrical resistant grade
glass, or a combination comprising at least one of the foregoing
glasses.
6. The film of claim 1 where the glass is an alkali resistant
glass.
7. The film of claim 1 wherein the glass is in the form of milled
fibers, chopped fibers, powder, flake or a combination comprising
of at least one of the foregoing forms.
8. The film of claim 1 wherein the glass has an aspect ratio of
greater than about 4 and less than about 60.
9. The film of claim 1, comprising about 50 to about 995 wt. %
thermoplastic resin and about 0.05 wt. % to 50 wt. % glass based on
the total weight of the film.
10. The film of claim 1, wherein the passivating agent, containing
a silicon hydride functionality is of the formula (10) or (11):
##STR00010##
11. A polycarbonate composition comprising in admixture: a
thermoplastic resin component comprising a polycarbonate; and a
glass having a refractive index that is within 0.04 of the
thermoplastic resin component, wherein the glass is essentially
free of compounds selected from the group consisting of aluminum
oxides, boron oxides, boric acids and a combination comprising at
least one of the foregoing; wherein the glass has been passivated
with a passivating agent containing a silicon hydride
functionality, wherein the passivating agent is of the formula (10)
or (11); ##STR00011## wherein m is greater than or equal to 1; the
sum of m and n is equal to about 10,000: m+p is 3 to about 1000;
R.sup.g and R.sup.i are each independently hydrogen, alkyl, aryl,
alkylaryl, alkoxy, aryloxy, haloalkyl, haloaryl, and haloalkylaryl;
R.sup.j and R.sup.k are each independently alkyl, aryl, alkylaryl,
alkoxy, aryloxy, haloalkyl, haloaryl, and haloalkylaryl; and
R.sup.h is trialkylsilyl, arylalkylsilyl, triarylsilyl, hydrogen,
alkyl, aryl, alkylaryl, haloalkyl or haloalkylaryl; wherein the
passivating agent containing a silicon hydride functionality is
present at 0.001 to about 1.0 wt. % of the polycarbonate
composition; and wherein the polycarbonate composition has a haze
of less than about 20%, a total transmittance of greater than about
70%, a coefficient of thermal expansion of about 20 to about 70
um/m/.degree. C. measured over a temperature range of 20.degree. C.
to 70.degree. C., and a melt viscosity of about 0.5 to about 30.0
cm.sup.3/10 min measured according to ASTM D1238 at 300.degree.
C.
12. The polycarbonate composition of claim 11, wherein the
passivating agent containing a silicon hydride functionality is of
the formula (10) or (11): ##STR00012##
13. The polycarbonate composition of claim 11, having a molecular
weight decrease, alter thermal processing at 300.degree. C. for 18
minutes, of less than about 30 percent of the initial weight
average molecular weight of the polycarbonate.
14. The polycarbonate composition of claim 11, having a melt volume
ratio of about 1.0 to about 20.0 cm.sup.3/10 min, measured at
300.degree. C. in accordance with ASTM D1238.
15. The polycarbonate composition of claim 11, having a heat
deflection temperature of about 120 to about 170.degree. C.
measured at 0.45 MPa at 23.degree. C. using 3.2 mm bars according
to ASTM D 648.
16. The polycarbonate composition of claim 11 having a Notched Izod
Impact of about 50 to about 200 Joules per meter (J/m), measured at
23.degree. C. using 3.2 mm bars according to ASTM D256.
17. The polycarbonate composition of claim 11 having a flexural
modulus of about 2,500 to about 10,000 MPa measured on a 3.2 mm bar
at 23.degree. C. according to ASTM D790.
18. A film comprising in admixture: a thermoplastic resin component
comprising a polycarbonate; and a glass having a refractive index
within 0.04 of the thermoplastic resin component, wherein the glass
contains greater than about 10 wt. % zirconia; wherein the glass is
essentially free of compounds selected from the group consisting of
aluminum oxides, boron oxides, boric acids and a combination
comprising at least one of the foregoing; wherein the glass has
been passivated with a passivating agent containing a silicon
hydride functionality, wherein the passivating agent is of the
formula (10) or (11); ##STR00013## wherein m is greater than or
equal to 1; the sum of m and n is equal to 1 to about 10,000; m+p
is 3 to about 1000; R.sup.g and R.sup.i are each independently
hydrogen, alkyl, aryl, alkylaryl, alkoxy, aryloxy, haloalkyl,
haloaryl, and haloalkylaryl; R.sup.j and R.sup.k are each
independently alkyl, aryl, alkylaryl, alkoxy, aryloxy, haloalkyl,
haloaryl, and haloalkylaryl; and R.sup.h is trialkylsilyl,
arylalkylsilyl, triarylsilyl, hydrogen, alkyl, aryl, alkylaryl,
haloalkyl, haloaryl or haloalkylaryl; wherein the passivating agent
containing a silicon hydride functionality is present at 0.001 to
about 1.0 wt. % of the polycarbonate composition; wherein the film
has a thickness of about 0.01 to about 3.0 mm; and wherein the film
composition has a haze of less than about 20%, a total
transmittance of greater than about 70%, and a coefficient of
thermal expansion of about 20 to about 70 um/m/.degree. C. measured
over a temperature range of 20 to 70.degree. C.
19. The film of claim 1, wherein the polycarbonate and glass
admixture has a molecular weight decrease, after thermal processing
at 300.degree. C. for 18 minutes, of less than about 30 percent of
to initial weight average molecular weight of the
polycarbonate.
20. The film of claim 1, wherein the polycarbonate and glass
admixture has a melt volume ratio of about 0.5 to about 30.0
cm.sup.3/10 min, measured at 300.degree. C. in accordance with ASTM
D1238.
Description
BACKGROUND OF INVENTION
The present invention relates to transparent films and
compositions, and in particular to transparent films for optical
applications.
Polycarbonate (PC) is an engineering thermoplastic resin with
excellent toughness and clarity. Due to its excellent performance
characteristics, polycarbonate is used in many applications
requiring optical quality, including compact disks, ophthalmic
lenses, and as diffuser films in backlit display devices.
Polycarbonate films offer a number of advantages over poly(ethylene
terephthalate) (PET), films including higher heat distortion
temperature (HDT), higher scratch resistance, and better
performance under stringent environmental conditions.
One of the major performance demands of a diffuser film is
dimensional stability. Generally, when polycarbonate films are used
in this application, portions of the film near the hot lamp may
expand, while film further from the lamp either does not expand or
does not expand to a similar extent, resulting in warping or
wrinkling in these portions of the film. This can lead to an
optical waving effect that is evident by sinusoidal oscillations in
luminance intensity across the display panel after exposure. This
problem may become progressively worse as the area of the film
increases, and as the environmental conditions become more
stringent. For larger displays like those in liquid crystalline
display television (LCD TV) there is a demand for more and brighter
fluorescent lamps, hence exposing the back lit module (BLM) and
display to higher temperatures.
There accordingly remains a need in the art for films that that
will remain flat over a wide temperature range, i.e., films that
are dimensionally stable and therefore non-waving in use. It would
be a further advantage of the film maintained a combination of
advantageous physical characteristics such as low haze, high
percent transmission (% T), low yellowing, and/or improved melt
stability. Such compositions can be used in making films that will
retain flatness over a wide range of end use conditions.
BRIEF DESCRIPTION OF THE INVENTION
In one embodiment there is provided a flat film comprising in
admixture a thermoplastic resin component comprising a
polycarbonate; and a glass having a refractive index within 0.04 of
the thermoplastic resin component, wherein the film composition has
a haze of less than about 20%, total transmittance of greater than
about 70%, and a coefficient of thermal expansion of about 20 to
about 70 um/m/.degree. C. measured over a temperature range of 20
to 70.degree. C.
In another embodiment there is provided an article comprising the
above film.
In another embodiment, a method of making a flat film having
improved resistance to waving comprises forming a film from a
polycarbonate composition comprising a thermoplastic resin
component comprising a polycarbonate; and a glass having a
refractive index within 0.04 of the thermoplastic resin component,
wherein the film composition has a haze of less than about 20%,
total transmittance of greater than about 70%, and a coefficient of
thermal expansion of about 20 to about 70 um/m/.degree. C. measured
over a temperature range of 20 to 70.degree. C.
In yet another embodiment there is provided a polycarbonate
composition comprising in admixture a thermoplastic resin component
comprising a polycarbonate; and a glass having a refractive index
that is within 0.04 of the thermoplastic resin component, and
wherein the polycarbonate composition has a haze of less than about
20%, a total transmittance of greater than about 70%, a coefficient
of thermal expansion of about 20 to about 70 um/m/.degree. C.
measured over a temperature range of 20.degree. C. to 70.degree.
C., and a melt viscosity of about 0.5 to about 30.0 cm.sup.3/10 min
measured according to ASTM D1238 at 300.degree. C.
In another embodiment there is provided a process of making a
polycarbonate composition comprising combining a thermoplastic
resin component comprising a polycarbonate with a glass having a
refractive index within 0.04 of the thermoplastic resin component,
wherein the polycarbonate composition has a haze of less than about
20%, total transmittance of greater than about 70%, a coefficient
of thermal expansion of about 20 to about 70 um/m/.degree. C.
measured over a temperature range of 20 to 70.degree. C., and a
melt viscosity of about 0.5 to about 30.0 cm.sup.3/10 min measured
according to ASTM D1238 at 300.degree. C.
In yet another embodiment there is provided an article comprising
the above polycarbonate composition.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph of the change in the inflow coefficient of
thermal expansion as the amount of glass loading increases.
FIG. 2 is a graph of the number of waves formed by a diffuser film
directly on top of a backlit module without an LCD panel as the
amount of glass loading increases.
FIG. 3 is a graph of the optical characterization results of haze
in various films as the amount of glass loading increases.
FIG. 4 is a graph of the optical characterization results of
transmission in various films as the amount of glass loading
increases.
DETAILED DESCRIPTION
It has been unexpectedly found by the inventors hereof that
compositions having a polycarbonate and a glass that closely
matches the refractive index of the polycarbonate can provide films
that retain their transparency, yet have lower warping and/or
wrinkling over a useful temperature range such as about 0 to about
100.degree. C., about 0.degree. to about 80.degree. C. and in other
case from about 20 to about 70.degree. C. In particular, the films
may have a low coefficient of thermal expansion ("CTE"); low
yellowing; low haze; high transmission, and/or high flexural
modulus. Such films, when heated in a constrained geometry, will
show better flatness, i.e., less waviness, than a higher CTE film.
The matched refractive index matched glasses preserve the optical
properties of the polycarbonates, such as high transmittance and
low haze.
It has further been found that in some instances the refractive
index matching glass adversely affects the melt stability of the
polycarbonate, which can result in a loss of properties and/or the
formation of voids or bubbles in the film. Passivation of the
glasses can prevent degradation of the polycarbonate resin during
melt processing to form the film. In particular, improved melt
stability may be obtained when the glasses are treated with a
silane compound.
The polycarbonate compositions may be used to form films, such as
flat films, of optical quality. In a particularly advantageous
feature, the films manufactured from these compositions may have
significantly reduced thermal distortion (waving) in applications
such as backlit displays with little to no degradation of the
luminance when compared to polycarbonate without glass.
The terms "polycarbonate" and "polycarbonate resin" means
compositions having repeating structural carbonate units of the
formula (1):
##STR00001## in which at least 60 percent of the total number of
R.sup.1 groups are aromatic organic radicals and the balance
thereof are aliphatic, alicyclic, or aromatic radicals. In one
embodiment, each R.sup.1 is an aromatic organic radical and,
preferably, a radical of the formula (2): -A.sup.1-Y.sup.1-A.sup.2-
(2) where each of A.sup.1 and A.sup.2 is a monocyclic divalent aryl
radical and Y.sup.1 is a bridging radical having one or two atoms
that separate A.sup.1 from A.sup.2. In an exemplary embodiment, one
atom separates A.sup.1 from A.sup.2. Illustrative non-limiting
examples of radicals of this type are --O--, --S--, --S(O)--,
--S(O.sub.2)--, --C(O)--, methylene, cyclohexylmethylene,
2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene,
neopentylidene, cyclohexylidene, cyclopentadecylidene,
cyclododecylidene, and adamantylidene. The bridging radical Y.sup.1
may be a hydrocarbon group or a saturated hydrocarbon group such as
methylene, cyclohexylidene, or isopropylidene.
Polycarbonates may be produced by the interfacial reaction of
dihydroxy compounds having the formula HO--R.sup.1--OH, which
includes dihydroxy compounds of formula (3)
HO-A.sup.1-Y.sup.1-A.sup.2-OH (3) wherein Y.sup.1, A.sup.1 and
A.sup.2 are as described above. Also included are bisphenol
compounds of general formula (4):
##STR00002## wherein R.sup.a and R.sup.b each represent a halogen
atom or a monovalent hydrocarbon group and may be the same or
different; p and q are each independently integers of 0 to 4; and
X.sup.a represents one of the groups of formula (5):
##STR00003## wherein R.sup.c and R.sup.d each independently
represent a hydrogen atom or a monovalent linear or cyclic
hydrocarbon group and R.sup.e is a divalent hydrocarbon group.
Some illustrative, non-limiting examples of suitable dihydroxy
compounds include the dihydroxy-substituted hydrocarbons disclosed
by name or formula (generic or specific) in U.S. Pat. No.
4,217,438. A nonexclusive list of specific examples of suitable
dihydroxy compounds includes the following: resorcinol,
4-bromoresorcinol, hydroquinone, 4,4'-dihydroxybiphenyl,
1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene,
bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)diphenylmethane,
bis(4-hydroxyphenyl)-1-naphthylmethane,
1,2-bis(4-hydroxyphenyl)ethane,
1,1-bis(4-hydroxyphenyl)-1-phenylethane,
2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane,
bis(4-hydroxyphenyl)phenylmethane,
2,2-bis(4-hydroxy-3-bromophenyl)propane, 1,1-bis
(hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane,
1,1-bis(4-hydroxyphenyl)isobutene,
1,1-bis(4-hydroxyphenyl)cyclododecane,
trans-2,3-bis(4-hydroxyphenyl)-2-butene,
2,2-bis(4-hydroxyphenly)adamantine, (alpha,
alpha'-bis(4-hydroxyphenyl)toluene,
bis(4-hydroxyphenyl)acetonitrile,
2,2-bis(3-methyl-4-hydroxyphenyl)propane,
2,2-bis(3-ethyl-4-hydroxyphenyl)propane,
2,2-bis(3-n-propyl-4-hydroxyphenyl)propane,
2,2-bis(3-isopropyl-4-hydroxyphenyl)propane,
2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane,
2,2-bis(3-t-butyl-4-hydroxyphenyl)propane,
2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,
2,2-bis(3-allyl-4-hydroxyphenyl)propane,
2,2-bis(3-methoxy-4-hydroxyphenyl)propane,
2,2-bis(4-hydroxyphenyl)hexafluoropropane,
1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene,
1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene,
1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene
4,4'-dihydroxybenzophenone, 3,3-bis(4-hydroxyphenyl)-2-butanone,
1,6-bis(4-hydroxyphenyl)-1,6-hexanedione, ethylene glycol
bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ether,
bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide,
bis(4-hydroxyphenyl)sulfone, 9,9-bis(4-hydroxyphenyl)fluorine,
2,7-dihydroxypyrene,
6,6'-dihydroxy-3,3,3',3'-tetramethylspiro(bis)indane
("spirobiindane bisphenol"), 3,3-bis(4-hydroxphenyl)phtalide,
2,6-dihydroxydibenzo-p-dioxin, 2,6-dihydroxythianthrene,
2,7-dihydroxyphenoxathin, 2,7-dihydroxy-9,10-dimethylphenazine,
3,6-dihydroxydibenzofuran, 3,6-dihydroxydibenzothiophene, and
2,7-dihydroxycarbazole, and the like, as well as mixtures
comprising the foregoing dihydroxy compounds.
A nonexclusive list of specific examples of the types of bisphenol
compounds that are represented by formula (3) includes
1,1-bis(4-hydroxyphenyl) methane, 1,1-bis(4-hydroxyphenyl) ethane,
2,2-bis(4-hydroxyphenyl) propane (hereinafter "bisphenol A" or
"BPA"), 2,2-bis(4-hydroxyphenyl) butane, 2,2-bis(4-hydroxyphenyl)
octane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyhenyl)
n-butane, 2,2-bis(4-hydroxy-1-methylphenyl) propane, and
1,1-bis(4-hydroxy-t-butylphenyl) propane. Combinations comprising
the foregoing dihydroxy compounds may also be used.
Branched polycarbonates are also useful, as well as blends of a
linear polycarbonate and a branched polycarbonate. The branched
polycarbonates may be prepared by adding a branching agent during
polymerization. These branching agents include polyfunctional
organic compounds containing at least three functional groups
selected from hydroxyl, carboxyl, carboxylic anhydride, haloformyl,
and combinations comprising at least one the foregoing functional
groups. Specific examples include trimellitic acid, trimellitic
anhydride, trimellitic trichloride, tris-p-hydroxy phenyl ethane,
isatin-bis-phenol, tris-phenol TC
(1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene), tris-phenol PA
(4(4(1,1-bis(p-hydroxyphenyl)ethyl) alpha, alpha-dimethyl
benzyl)phenol), 4-chloroformyl phthalic anhydyride, trimesic acid,
and benzophenone tetracarboxylic acid. The branching agents are
added at a level of 0.05 to 2.0 weight percent (wt. %). Branching
agents and procedures for making branched polycarbonates are
described in U.S. Pat. Nos. 3,635,895 and 4,001,184, which are
incorporated by reference. All types of polycarbonate end groups
are contemplated as being useful in the polycarbonate
composition.
"Polycarbonates" and "polycarbonate resins" as used herein further
includes copolymers or blends of polycarbonates with other
copolymers comprising carbonate chain units. A specific suitable
copolymer is a polyestercarbonate, also known as a
copolyester-polycarbonate. Such copolymers further contain, in
addition to recurring carbonate chain units of the formula (1),
repeating units of formula (6)
##STR00004## wherein D is a divalent radical derived from a
dihydroxy compound, and may be, for example, a C.sub.2-10 alkylene
radical, a C.sub.6-20 alicyclic radical, a C.sub.6-20 aromatic
radical or a polyoxyalkylene radical in which the alkylene groups
contain 2 to 6 carbon atoms, specifically 2, 3, or 4 carbon atoms;
and T is a divalent radical derived from a dicarboxylic acid, and
is, for example, a C.sub.2-10 alkylene radical, a C.sub.6-20
alicyclic radical, a C.sub.6-20 alkyl aromatic radical, or a
C.sub.6-20 aromatic radical.
In one embodiment, D is a C.sub.2-6 alkylene radical. In another
embodiment, D is derived from an aromatic dihydroxy compound of
formula (7):
##STR00005## wherein each R.sup.f is independently a halogen atom,
a C.sub.1-10 hydrocarbon group, or a C.sub.1-10 halogen substituted
hydrocarbon group, and n is 0 to 4. In one embodiment, the halogen
is bromine. Examples of compounds that may be represented by the
formula (7) include resorcinol, substituted resorcinol compounds
such as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl
resorcinol, 5-butyl resorcinol, 5-t-butyl resorcinol, 5-phenyl
resorcinol, 5-cumyl resorcinol, 2,4,5,6-tetrafluororesorcinol,
2,4,5,6-tetrabromo resorcinol, or the like; catechol; hydroquinone;
substituted hydroquinones such as 2-methyl hydroquinone, 2-ethyl
hydroquinone, 2-propyl hydroquinone, 2-butyl hydroquinone,
2-t-butyl hydroquinone, 2-phenyl hydroquinone, 2-cumyl
hydroquinone, 2,3,5,6-tetramethyl hydroquinone,
2,3,5,6-tetra-t-butyl hydroquinone,
2,3,5,6-tetrafluorohydroquinone, 2,3,5,6-tetrabromo hydroquinone,
or the like; or combinations comprising at least one of the
foregoing compounds.
Examples of aromatic dicarboxylic acids that may be used to prepare
the polyesters include isophthalic or terephthalic acid,
1,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether,
4,4'-bisbenzoic acid, and combinations comprising at least one of
the foregoing acids. In one embodiment acids containing fused rings
can also be present, such as in 1,4-, 1,5-, or
2,6-naphthalenedicarboxylic acids. The dicarboxylic acids may be,
for example, terephthalic acid, isophthalic acid, naphthalene
dicarboxylic acid, cyclohexane dicarboxylic acid, or combinations
comprising at least one of the foregoing dicarboxylic acids. In
another embodiment a dicarboxylic acid comprises a mixture of
isophthalic acid and terephthalic acid where the weight ratio of
terephthalic acid to isophthalic acid is 10:1 to 0.2:9.8. In
another specific embodiment, D is a C.sub.2-6 alkylene radical and
T is p-phenylene, m-phenylene, naphthalene, a divalent
cycloaliphatic radical, or a combination comprising at least one of
the foregoing. This class of polyester includes the poly(alkylene
terephthalates).
Another useful type of polycarbonate is a
polysiloxane-polycarbonate copolymer having polydiorganosiloxane
blocks comprising repeating structural units of formula (8):
##STR00006## wherein each occurrence of R is same or different, and
is a C.sub.1-13 monovalent organic radical. For example, R may be a
C.sub.1 C.sub.13 alkyl group, C.sub.1 C.sub.13 alkoxy group,
C.sub.2 C.sub.13 alkenyl group, C.sub.2 C.sub.13 alkenyloxy group,
C.sub.3 C.sub.6 cycloalkyl group, C.sub.3 C.sub.6 cycloalkoxy
group, C.sub.6 C.sub.10 aryl group, C.sub.6 C.sub.10 aryloxy group,
C.sub.7 C.sub.13 aralkyl group, C.sub.7 C.sub.13 aralkoxy group,
C.sub.7 C.sub.13 alkaryl group, or C.sub.7 C.sub.13 alkaryloxy
group. Combinations of the foregoing R groups may be used in the
same copolymer.
D in formula (8) is selected so as to provide an effective level of
transparency to the polycarbonate composition. The value of D will
therefore vary widely depending on the type and relative amount of
each component in the thermoplastic composition, the desired
properties of the composition, and like considerations. Generally,
D may have an average value of 2 to about 1000, specifically 2 to
about 500, more specifically about 5 to about 100. In one
embodiment, D has an average value of about 10 to about 75, and in
still another embodiment, D has an average value of about 40 to
about 60. Where D is of a lower value, e.g., less than about 40, it
may be desirable to use a relatively larger amount of the
polysiloxane-polycarbonate copolymer. Conversely, where D is of a
higher value, e.g., greater than about 40, it may be necessary to
use a relatively lower amount of the polysiloxane-polycarbonate
copolymer. A combination of a first and a second (or more)
polysiloxane-polycarbonate copolymers may be used, wherein the
average value of D of the first copolymer is less than the average
value of D of the second copolymer.
In one embodiment the polydiorganosiloxane blocks comprise
repeating structural units of formula (9)
##STR00007## wherein each occurrence of R is same or different, and
is a C.sub.1-13 monovalent organic radical. For example, R may be a
C.sub.1 C.sub.13 alkyl group, C.sub.1 C.sub.13 alkoxy group,
C.sub.2 C.sub.13 alkenyl group, C.sub.2 C.sub.13 alkenyloxy group,
C.sub.3 C.sub.6 cycloalkyl group, C.sub.3 C.sub.6 cycloalkoxy
group, C.sub.6 C.sub.10 aryl group, C.sub.6 C.sub.10 aryloxy group,
C.sub.7 C.sub.13 aralkyl group, C.sub.7 C.sub.13 aralkoxy group,
C.sub.7 C.sub.13 alkaryl group, or C.sub.7 C.sub.13 alkaryloxy
group. Combinations of the foregoing R groups may be used in the
same copolymer. R.sup.2 in formula (9) is a divalent C.sub.1
C.sub.8 aliphatic group. Each M in formula (9) may be the same or
different, and may be a halogen, cyano, nitro, C.sub.1 C.sub.8
alkylthio, C.sub.1 C.sub.8 alkyl, C.sub.1 C.sub.8 alkoxy, C.sub.2
C.sub.8 alkenyl, C.sub.2 C.sub.8 alkenyloxy group, C.sub.3 C.sub.8
cycloalkyl, C.sub.3 C.sub.8 cycloalkoxy, C.sub.6 C.sub.10 aryl,
C.sub.6 C.sub.10 aryloxy, C.sub.7 C.sub.12 aralkyl, C.sub.7
C.sub.12 aralkoxy, C.sub.7 C.sub.12 alkaryl, or C.sub.7 C.sub.12
alkaryloxy, wherein each n is independently 0, 1, 2, 3, or 4.
In one embodiment, M is independently bromo or chloro, a C.sub.1
C.sub.3 alkyl group such as methyl, ethyl, or propyl, a C.sub.1
C.sub.3 alkoxy group such as methoxy, ethoxy, or propoxy, or a
C.sub.6 C.sub.7 aryl group such as phenyl, chlorophenyl, or tolyl;
R.sup.2 is a dimethylene, trimethylene or tetramethylene group; and
R is a C.sub.1-8 alkyl, haloalkyl such as trifluoropropyl,
cyanoalkyl, or aryl such as phenyl, chlorophenyl or tolyl. In
another embodiment, R is methyl, or a mixture of methyl and
trifluoropropyl, or a mixture of methyl and phenyl. In still
another embodiment, M is methoxy, n is one, R.sup.2 is a divalent
C.sub.1 C.sub.3 aliphatic group, and R is methyl.
Generally, the amount of dihydroxy polydiorganosiloxane is selected
so as to produce a copolymer comprising about 0.1 to about 20 mole
percent of polydiorganosiloxane blocks relative to the moles of
polycarbonate blocks, and more specifically, about 0.5 to about 12
mole percent of polydiorganosiloxane blocks relative to the moles
of polycarbonate blocks. The polysiloxane-polycarbonate copolymers
are preferably transparent, and can have a weight-average molecular
weight (measured, for example, by gel permeation chromatography,
ultra-centrifugation, or light scattering) of about 10,000 to about
200,000, specifically about 20,000 to about 100,000. The
polysiloxane-polycarbonate copolymers may have a weight-average
molecular weight of about 15,000 to about 100,000. Suitable
transparent polysiloxane-polycarbonate copolymers are commercially
available from GE Plastics.
Some polycarbonates are based on bisphenol A, in which each of
A.sup.1 and A.sup.2 are p-phenylene and Y.sup.1 is isopropylidene.
In one embodiment, the weight average molecular weight of the
polycarbonate is about 10,000 to about 100,000, specifically about
20,000 to about 50,000, more specifically about 25,000 to about
40,000, as determined by gel permeation chromatography in
dichloromethane using polystyrene standards. Combinations of
polycarbonates of different molecular weights may be used.
Suitable polycarbonates can be manufactured by processes such as
interfacial polymerization and melt polymerization. Although the
reaction conditions for interfacial polymerization may vary, an
exemplary process generally involves dissolving or dispersing a
dihydric phenol reactant in aqueous caustic soda or potash, adding
the resulting mixture to a suitable water-immiscible solvent
medium, and contacting the reactants with a carbonate precursor in
the presence of a suitable catalyst such as triethylamine or a
phase transfer catalyst, and under controlled pH conditions, for
example at a pH of about 8 to about 10. The most commonly used
water immiscible solvents include methylene chloride,
1,2-dichloroethane, chlorobenzene, toluene, and the like. Suitable
carbonate precursors include, for example, a carbonyl halide such
as carbonyl bromide or carbonyl chloride, or a haloformate such as
a bishaloformates of a dihydric phenol (e.g., the bischloroformates
of bisphenol A, hydroquinone, or the like) or a glycol (e.g., the
bishaloformate of ethylene glycol, neopentyl glycol, polyethylene
glycol, or the like). Combinations comprising at least one of the
foregoing types of carbonate precursors may also be used.
Among the preferred phase transfer catalysts that may be used are
catalysts of the formula (R.sup.3).sub.4Q.sup.+X, wherein each
R.sup.3 is the same or different, and is a C.sub.1-10 alkyl group;
Q is a nitrogen or phosphorus atom; and X is a halogen atom or a
C.sub.1-8 alkoxy group or C.sub.6-188 aryloxy group. Suitable phase
transfer catalysts include, for example,
[CH.sub.3(CH.sub.2).sub.3].sub.4NX,
[CH.sub.3(CH.sub.2).sub.3].sub.4PX,
[CH.sub.3(CH.sub.2).sub.5].sub.4NX,
[CH.sub.3(CH.sub.2).sub.6].sub.4NX,
[CH.sub.3(CH.sub.2).sub.4].sub.4NX,
CH.sub.3[CH.sub.3(CH.sub.2).sub.3].sub.3NX,
CH.sub.3[CH.sub.3(CH.sub.2).sub.2].sub.3NX wherein X is Cl.sup.-,
Br.sup.-, or a C.sub.1-8 alkoxy group or C.sub.6-188 aryloxy group.
An effective amount of a phase transfer catalyst may be about 0.1
to about 10 wt. % based on the weight of bisphenol in the
phosgenation mixture. In another embodiment an effective amount of
phase transfer catalyst may be about 0.5 to about 2 wt. % based on
the weight of bisphenol in the phosgenation mixture.
Alternatively, melt processes may be used. Generally, in the melt
polymerization process, polycarbonates may be prepared by
co-reacting, in a molten state, the dihydroxy reactant(s) and a
diaryl carbonate ester, such as diphenyl carbonate, in the presence
of a transesterification catalyst in a Banbury mixer, twin screw
extruder, or the like to form a uniform dispersion. Volatile
monohydric phenol is removed from the molten reactants by
distillation and the polymer is isolated as a molten residue.
The copolyester-polycarbonate resins are also prepared by
interfacial polymerization technique, well known to those skilled
in the art (see, for example, U.S. Pat. Nos. 3,169,121 and
4,487,896). Rather than utilizing the dicarboxylic acid per se, it
is possible, and sometimes even preferred, to employ the reactive
derivatives of the acid, such as the corresponding acid halides, in
particular the acid dichlorides and the acid dibromides. Thus, for
example instead of using isophthalic acid, terephthalic acid, or
mixtures thereof, it is possible to employ isophthaloyl dichloride,
terephthaloyl dichloride, and mixtures thereof.
In addition to the polycarbonates described above, it is also
possible to use combinations of the polycarbonate resins with other
thermoplastic polymers, for example combinations of polycarbonates
and/or polycarbonate copolymers with polyesters, provided that the
combination do not significantly impair the desired properties of
the compositions, for example the transparency and/or melt
stability of the composition. In one embodiment, the haze of the
polycarbonate and other thermoplastic polymer is less than about
50%, more specifically less than about 25%, even more specifically
less than about 10%. As used herein, a "combination" is inclusive
of all mixtures, blends, alloys, and the like.
Suitable polyesters include, for example, poly(alkylene
dicarboxylates), liquid crystalline polyesters, and polyester
copolymers. It is also possible to use a branched polyester in
which a branching agent, for example, a glycol having three or more
hydroxyl groups or a trifunctional or multifunctional carboxylic
acid had been incorporated. Furthermore, it is sometime desirable
to have various concentrations of acid and hydroxyl end groups on
the polyester, depending on the ultimate end-use of the
composition. In one embodiment, specific examples of suitable
polyesters include poly(ethylene terephthalate) (PET),
poly(1,4-butylene terephthalate) (PBT), (polypropylene
terephthalate) (PPT), polycyclohexanedimethanol terephthalate
(PCT), polycyclohexanedimethanol cyclohexane dicarboxylate (PCCD)
and combinations comprising at least one of the foregoing
polyesters or copolymers containing the aforementioned ester
linkages. Also contemplated are the above polyesters with a minor
amount, e.g., about 0.5 to about 20 percent by weight, of units
derived from an aliphatic diacid and/or an aliphatic polyol to make
copolyesters.
In one embodiment, the weight average molecular weight of the
polyester is about 1,000 to about 100,000, specifically about 2,000
to about 50,000, more specifically less than about 25,000. It is
believed that lower molecular weight polyesters are more miscible,
and therefore provide combinations having lower haze. Molecular
weight may be determined by gel permeation chromatography in
dichloromethane using polystyrene standards. Combinations of
polyesters of different molecular weights may be used.
The blends of a polycarbonate and a polyester may comprise about 1
to about 99 wt. % polycarbonate and correspondingly about 1 to
about 99 wt. % polyester, in particular a polyester containing
cycloaliphatic repeat units, specifically a cyclohexyl ring. In one
embodiment, the blend comprises about 70 to about 99 wt. %
polycarbonate and correspondingly about 1 to about 30 wt. % PCT or
PCCD. The foregoing amounts are base on the total weight of the
polycarbonate resin and polyester resin. Again, the amounts of any
polyester will be selected so as to provide a composition with low
haze.
The polycarbonate compositions further comprise a glass to provide
reinforcement and dimensional stability to the compositions. In an
important feature, the glass is selected so as to provide the
desired balance of optical and physical properties to the
composition, in particular transparency (as reflected by low haze
and high transmissivity) and optionally low yellowness in
combination with low coefficient of thermal expansion and high
flexural modulus. To achieve these properties, the refractive index
of the glass is matched to that that of the thermoplastic resin
component (polycarbonate and any other thermoplastic polymer) to
within 0.04, that is, the refractive index of the glass and the
thermoplastic resin component have values that are within 0.04 of
each other over a useful temperature range. It has unexpectedly
been found that such matching will provide a composition that has
an excellent combination of optical and physical properties, in
particular transparency and dimensional stability. Films made of
such a composition will have lower CTE and improved flatness, with
less tendency toward waviness, while still retaining high
transparency and low haze.
In one embodiment the glass has a refractive index that is
substantially equivalent to the refractive index of the
thermoplastic resin component over a temperature range of about
0.degree. to about 80.degree. C. A glass having a substantially
equivalent refractive index has a refractive index that is about
0.001 units to about 0.04 units greater than or less than the
refractive index of the resin component, specifically about 0.005
units to about 0.03 units greater than or less than the refractive
index of the thermoplastic resin component. The refractive index of
the glass is matched to that of the thermoplastic resin component
over a temperature range of about 0 to about 100.degree. C.,
specifically about 0.degree. to about 80.degree. C., and in other
cases about 20 to about 70.degree. C. Outside the stated ranges of
refractive index and/or temperature, the polycarbonate composition
may significantly lose transparency.
Different glasses may be used, such as alkali resistant glass,
dense barium crown glass, electrical resistant grade glass, and
combinations comprising at least one of the foregoing glasses.
Other examples of useful glasses are those identified as "E-glass,"
"D-glass," "R-glass," E-glass derivatives that are fluorine-free
and/or boron-free, and the like, providing they meet the refractive
index matching criteria with the resin component as described
above. Amounts (percent by weight) of the various components for
certain glasses is set forth in Table 1 below.
TABLE-US-00001 TABLE 1 Component D-Glass E-Glass R-Glass SiO.sub.2
72 75 52 56 55 65 Al.sub.2O.sub.3 0 1 12 16 15 30 B.sub.2O.sub.3 21
24 5 10 CaO 0 1 16 25 9 25 MgO 0 5 3 8 ZnO BaO Li.sub.2O Na.sub.2O
+ K.sub.2O 0 4 0 2 0 1 TiO.sub.2 0 1.5 ZrO.sub.2 Fe.sub.2O.sub.3 0
0.3 0 0.8 F 0 1 0 0.3
The glass may be a borosilicate glass that is essentially free of
one or more compounds selected from the group consisting of
aluminum oxides, boron oxides, and boric acids. In one embodiment
the glass is a borosilicate glass that contains less than about 1
wt. % of any one of aluminum oxides, boron oxides, or boric acids.
In another embodiment the glass is a borosilicate glass that
contains less than about 1 wt. % of any two of aluminum oxides,
boron oxides, and boric acids. In another embodiment, the glass is
a borosilicate glass than contains less than about 1 wt. % of
aluminum oxides, less than about 1 wt. % of boron oxides, and less
than about 1 wt. % boric acids. In a specific type of borosilicate
glass, the total weight of any aluminum oxides, boron oxides, and
boric acids is less than about 1 wt. % of the total weight of the
glass.
In another embodiment the glass contains at least about 10 wt. %
zirconium oxide ("zirconia"). A glass with a high percentage of
zirconia, for instance greater than about 15 wt. % zirconia, may be
desirable for refractive index matching and CTE reduction. The
glass may comprise about 10 to about 25 wt. % zirconia, or about 18
to about 45 wt. % zirconia. One suitable zirconium oxide glass is
available in the form of milled fibers from Nippon Electric Glass
under the trade designation ARG fiber (GAP-50). This glass has a
specific gravity of 2.72, with a refractive index of 1.594 at
587.56 nanometers (nm), a tensile strength of 1.4 GPa, a maximum
elongation of 4 to 2%, an alkali resistivity in a saturated cement
solution at 80.degree. C., for 90 hours, with a weight loss of
0.8%. The composition is believed to comprise 61 wt. % SiO.sub.2,
17.5 wt. % (Na.sub.2O+K.sub.2O+Li.sub.2O), 19.5 wt. % ZrO.sub.2;
and 2 wt. % (TiO.sub.2+Fe.sub.2O.sub.3). It is substantially free
of alumina and boron-containing components.
The amount of glass that may generally be used is about 0.05 to
about 50 wt. %, specifically about 1 to about 30 wt. %, and more
specifically about 5 to about 20 wt. % based on the combined weight
of the total filled polycarbonate composition (resin component,
glass, and other optional additives as described below). Outside
these ranges of glass, the polycarbonate composition may have too
high a CTE or may be difficult to melt process. Generally, the
glass is particulate, and may be in the form of milled fibers,
chopped fibers, powders, flakes, and combinations comprising at
least one of the foregoing forms. There is no particular limitation
to the shape of the refractive index matching particles, which may
be for example, spherical, cylindrical, irregular, plate-like, or
fiber-like.
The average largest dimension of the glass particles is generally
selected so as to provide the desired balance of optical and
physical properties in the filled polycarbonate composition, taking
into account any breakage or other decrease in size that may occur
during processing of the composition, i.e., during manufacture of
the composition into a form suitable for the formation of articles.
For example, when in fibrous form, the glass is selected to provide
a post-processing aspect ratio (the average ratio of length to
diameter (L/d) of the fibers) of up to about 60. The
post-processing ratio may further be about 4 to about 50,
specifically about 10 to about 40, and more specifically about 20
to about 30. Suitable average diameters of fibrous forms may be
about 1 to about 24 micrometers, specifically about 5 to about 22
micrometers and more specifically about 10 to about 13 micrometers.
Use of non-round fiber cross sections is possible. For other
particulate shapes, the average largest diameter of the glass
post-processing may be about 1 to about 20 micrometers,
specifically about 3 to about 15 micrometers and more specifically
about 4 to about 14 micrometers. Bimodal or higher particle size
distributions may also be used. Longer aspect ratios often give
better mechanical properties than shorter fibers but may also lead
to anisotropy in the film that will be undesirable. In some cases
milled glass fibers provide a good balance of properties. A mixture
of glass shapes, for instance fibers and flake, can also sometimes
be used to advantage.
The glasses may be manufactured by standard processes, for example,
by steam or air blowing, flame blowing or mechanical pulling. Glass
fibers may be hammer milled to make smaller fibers of various
sizes. Glass flakes may be made by several processes, for example
by crushing glass bubbles. The glass fibers used in polycarbonate
reinforcement are frequently made by mechanical pulling. In one
embodiment, the glass fibers are made through an all-electric
melting furnace system.
It has further been found that passivation of the glass on at least
a portion of its surface can contribute to the balance of
properties desired for applications such as back-lit diffuser
films. Use of passivated glass accordingly provides a polycarbonate
composition with improved melt stability, while still maintaining
the unique combination of the above noted physical properties.
While not being restricted by any mechanism, it is thought that the
passivation agent chemically reacts with sites in the refractive
index matching glass to render them inert to reactions that would
cause degradation of the polycarbonate.
The passivation agent is selected for compatibility with resin
component, particularly the polycarbonate, and its ability to
deactivate any active sites on the glass surface that may
contribute to resin decomposition. This is in contrast to standard
glass treatments, which are generally selected to increase the
reactivity of the glass with the matrix, to improve adhesion, for
example. While the present passivation process may result in
improved adhesion (due to improved wet-out for example), together
with the improved melt stability, it is not the primary purpose of
passivation. The type and amount of passivating agent is further
selected so as to not significantly adversely affect the optical
properties and the CTE of the filled polycarbonate composition.
In one embodiment, the passivation agent is a silane, i.e., a
compound having a silicon-hydrogen bond. Suitable pasaivation
agents include, for example silane compounds of the general formula
(10) and (11):
##STR00008## wherein m is greater than or equal to 1;the sum of m
and n is equal to 1 to about 10,000; m+p is 3 to about 1000;
R.sup.g and R.sup.i are each independently hydrogen, alkyl, aryl,
alkylaryl, alkoxy, aryloxy, haloalkyl, haloaryl, and haloalkylaryl;
R.sup.j and R.sup.k are each independently alkyl, aryl, alkylaryl,
alkoxy, aryloxy, haloaryl, haloaryl, and haloalkylaryl; and R.sup.h
is trialkylsilyl, arylalkylsilyl, triarylsilyl, hydrogen, alkyl,
aryl, alkylaryl, haloalkyl, haloaryl or haloalkylaryl.
In some instances of formula (10), R.sup.g and R.sup.i may each
independently be hydrogen, methyl, ethyl, propyl, trifluoropropyl,
phenyl, ethylphenyl, methoxy, ethoxy, and phenoxy; R.sup.j and
R.sup.k are each independently methyl, ethyl, propyl,
trifluoropropyl, phenyl, ethylphenyl, methoxy, ethoxy, and phenoxy;
and R.sub.5 is hydrogen, methyl, ethyl, propyl, trifluoropropyl,
phenyl, or ethylphenyl. In some instances of formula (11), R.sup.i
may be hydrogen, methyl, ethyl, propyl, trifluoropropyl, phenyl, or
ethylphenyl; and R.sup.j and R.sup.k are each independently methyl,
ethyl, propyl, trifluoropropyl, phenyl, ethylphenyl, methoxy,
ethoxy, and phenoxy. Mixtures of passivation agents may also be
used. A suitable passivation agent is a silicone fluid available
under the trade name DF1040 from GE Silicones, which is a trimethyl
silyl-capped methyl hydrogen silicone of formula 10 wherein R.sup.g
and R.sup.i are methyl, R.sup.h is a trimethyl silyl, n=0 and
m=about 16.
It has been found that careful adjustment of the molecular weight
and amount of silicon hydride passivating agents such as those
described by formulas (10) and (11) results in compositions with
both improved melt stability and excellent optical and physical
properties. If too much of the passivating agent is used with too
high a molecular weight, it may increase melt stability but also
increase haze. In contrast, by excessively lowering the molecular
weight of the passivating agent, the passivating agent can become
too volatile and will escape the machinery during standard
processing temperatures, for example 300.degree. C. One embodiment,
the type, amount, and molecular weight of the passivating agent is
selected to provide compositions with a percent haze of below about
20% and a glass transition temperature (Tg) of greater than about
120.degree. C. Still further, the type, amount, and molecular
weight of the passivating agent may be selected so as to maintain
the desired color of the composition, i.e., to shift the color of
the composition by less than about 10 delta E units, specifically
less than 5 delta E units.
To achieve these results, the silane compound generally has a
molecular weight of about 100 to about 10,000, specifically about
200 to about 5000 and more specifically about 200 to about 1000
absolute molecular weight. In one possible embodiment, compounds of
formulas 10 and 11 wherein m+n=3 to about 100 and m+p=3 to about 50
may be desired to provide less volatility but still be of low
enough molecular weight to retain good optical properties. The
silane compound may be used in an amount of about 0.001 to about
5.0 wt. % of the filled polycarbonate composition at a molecular
weight of about 500, specifically in an amount of about 0.001 to
about 1.0 wt. % of the filled polycarbonate composition at a
molecular weight of about 500, and more specifically in an amount
of about 0.01 to about 0.5 wt. % of the filled polycarbonate
composition at a molecular weight of about 500. In some instances
where a silane passivation technique is employed, the composition
will retain at least about 70% of its original weight average
molecular weight (Mw), as measured by gel permeation
chromatography, after melt processing at about 300 .degree. C.
Methods of treating glasses with a passivating agent are varied and
known to those skilled in the art. In one particular aspect of
treating the glass, a number of particles, e.g., filaments, may be
formed simultaneously, treated with the passivating agent, and then
bundled into what is called a strand. Alternatively the strand
itself may be first formed of filaments and then treated with the
passivating agent. In another embodiment, the passivating agent is
added to the glass during processing of the filled polycarbonate
composition as described below. Often the glass, especially if used
in a milled, powder of flake form, may be blended with the
passivation agent prior to melt blending with the polycarbonate
resin.
The polycarbonate compositions may be manufactured by methods
generally available in the art, for example, in one embodiment,
powdered polycarbonate resin, glass, and other optional components
(including the passivating agent) are first blended, for example in
a Henschel high speed mixer or paint shaker. Other low shear
processes such as hand mixing or tumble blending, may also be
used.
The blend may then be fed into the throat of an extruder via a
hopper. The extruder is generally operated at a temperature higher
than that necessary to cause the composition to flow. Standard melt
processing conditions may be used, for example temperatures from
250 to 350.degree. C., specifically temperatures from 275 to
300.degree. C. with screw speeds of 50 to 400 rotations per minute
(rpm), specifically 100 to 300 rpm. Processing can be done on
single screw or twin-screw extruders or other processing equipment.
Vacuum venting is often beneficial as is drying the components
prior to mixing. Passivating agents may be metered into the mixing
devices during compounding. Alternatively, one or more of the
components may be incorporated into the composition by feeding
directly into the extruder at the throat and/or downstream through
a side stuffer. Additives (including the passivating agent) may
also be compounded into a masterbatch with the glass and fed into
the extruder.
The extrudate is generally immediately quenched in a water batch
and pelletized. The pellets so prepared when cutting the extrudate
may be about one-fourth inch (6.35 millimeters (mm)) long, or less,
and contain finely divided, uniformly dispersed glass in the blend
composition. Such pellets may be used for subsequent molding,
shaping, or forming.
In addition to glass and a resin component (polycarbonate and other
optional polymer), the polycarbonate composition may further
include various components and other additives ordinarily
incorporated in resin compositions of this type, for example impact
modifiers, fillers, heat stabilizers, light stabilizers,
antioxidants, mold release agents, lubricants, flame retardants,
anti-drip agents, and the like, as well as combinations of various
types of additives. It is to be understood that the type and
amounts of such components and additives are selected so as to not
significantly adversely affect the desired properties of the
compositions, in particular haze, transparency, and coefficient of
thermal expansion as described in more detail below.
Suitable heat stabilizers include, for example, phosphites,
phosphonites, mixtures of phosphites, phosphonites, hindered phenol
antioxidants and combinations comprising at least one of the
foregoing heat stabilizers. Heat stabilizers are generally present
in amounts of about 0.001 to about 1.0 parts by weight, based on
100 parts by weight of the resin component.
Suitable antioxidants include, for example, phosphonates,
organophosphites such as tris(nonyl phenyl)phosphite,
tris(2,4-di-t-butylphenyl)phosphite,
bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl
pentaerythritol diphosphite or the like; alkylated monophenols or
polyphenols; alkylated reaction products of polyphenols with
dienes, such as
tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]
methane, or the like; butylated reaction products of para-cresol or
dicyclopentadiene; alkylated hydroquinones; hydroxylated
thiodiphenyl ethers; alkylidene-bisphenols; benzyl compounds;
esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid
with monohydric or polyhydric alcohols; esters of
beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with
monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl
compounds such as distearylthiopropionate, dilaurylthiopropionate,
ditridecylthiodipropionate,
octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,
pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate
or the like; amides of
beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid or the
like, or combinations comprising at least one of the foregoing
antioxidants. Antioxidants are generally used in amounts of about
0.001 to about 1.0 part by weight, based on 100 parts by weight of
the resin component.
Suitable light stabilizers include, for example, benzotriazoles
such as 2-(2-hydroxy-5-methylphenyl)benzotriazole,
2-(2-hydroxy-5-tert-octylphenyl)benzotriazole and
2-hydroxy-4-n-octoxy benzophenone or the like or combinations
comprising at least one of the foregoing light stabilizers. Light
stabilizers are generally used in amounts of about 0.1 to about
10.0 parts by weight, based on 100 parts by weight of the resin
component.
Suitable antistatic agents include, for example, glycerol
monostearate, sodium stearyl sulfonate, sodium
dodecylbenzenesulfonate or the like, or combinations of the
foregoing antistatic agents. In one instance phosphonium salts of
fluorinated alkyl sulfonic acids, such as may be used. The
phosphonium sulfonate may be fluorinated phosphonium sulfonate and
is composed of a fluorocarbon containing an organic sulfonate anion
and an organic phosphonium cation. Examples of such organic
sulfonate anions include perfluoro methane sulfonate, perfluoro
butane sulfonate, perfluoro hexane sulfonate, perfluoro heptane
sulfonate, and perfluoro octane sulfonate. Examples of the
aforementioned phosphonium cation include aliphatic phosphonium
such as tetramethyl phosphonium, tetraethyl phosphonium, tetrabutyl
phosphonium, triethylmethyl phosphonium, tributylmethyl
phosphonium, tributylethyl phosphonium, trioctylmethyl phosphonium,
trimethylbutyl phosphonium trimethyloctyl phosphonium,
trimethyllauryl phosphonium, trimethylstearyl phosphonium,
triethyloctyl phosphonium and aromatic phosphoniums such as
tetraphenyl phosphonium, triphenylmethyl phosphonium,
triphenylbenzyl phosphonium, tributylbenzyl phosphonium. Antistatic
agents are generally used in amounts of about 0.1 to about 10 parts
by weight, based on 100 parts by weight of the resin component.
Suitable mold releasing agents include for example, stearyl
stearate, pentaerythritol tetrastearate, beeswax, montan wax,
paraffin wax, or the like, or combinations comprising at least one
of the foregoing mold release agents. Mold releasing agents are
generally used in amounts of about 0.01 to about 5.0 parts by
weight, based on 100 parts by weight of the resin component.
Suitable UV absorbers include for example, hydroxybenzophenones;
hydroxybenzotriazoles; hydroxybenzotriazines; cyanoacrylates;
oxanilides; benzoxazinones;
2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol
(CYASORB 5411); 2-hydroxy-4-n-octyloxybenzophenone (CYASORB 531);
2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol
(CYASORB 1164); 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one)
(CYASORB UV-3638);
1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,-
3-diphenylacryloyl)oxy]methyl]propane (UVINUL 3030);
2,2'-(1,4-phenylene) bis(4H-3,1-benzoxazin-4-one);
1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenyl-
acryloyl)oxy]methyl]propane; nano-size inorganic materials such as
titanium oxide, cerium oxide, and zinc oxide, all with particle
size less than about 100 nanometers; or the like, or combinations
comprising at least one of the foregoing UV absorbers. Such
nanoparticles may also need to be passivated as described herein to
give polycarbonate blends with good melt stability. UV absorbers
are generally used in amounts of about 0.10 to about 0.35 parts by
weight, based on 100 parts by weight of the resin component.
Suitable lubricants include for example, fatty acid esters such as
alkyl stearyl esters, e.g., methyl stearate or the like; mixtures
of methyl stearate and hydrophilic and hydrophobic surfactants
comprising polyethylene glycol polymers, polypropylene glycol
polymers, and copolymers thereof e.g., methyl stearate and
polyethylene-polypropylene glycol copolymers in a suitable solvent;
or combinations comprising at least one of the foregoing
lubricants. Lubricants are generally used in amounts of about 0.1
to about 5.0 parts by weight, based on 100 parts by weight of the
resin component.
Suitable dyes include, for example, organic dyes such as coumarin
460 (blue), coumarin 6 (green), nile red or the like; lanthanide
complexes; hydrocarbon and substituted hydrocarbon dyes; polycyclic
aromatic hydrocarbons; scintillation dyes (preferably oxazoles and
oxadiazoles); aryl- or heteroaryl-substituted poly (2 8 olefins);
carbocyanine dyes; phthalocyanine dyes and pigments; oxazine dyes;
carbostyryl dyes; porphyrin dyes; acridine dyes; anthraquinone
dyes; arylmethane dyes; azo dyes; diazonium dyes; nitro dyes;
quinone imine dyes; tetrazolium dyes; thiazole dyes; perylene dyes,
perinone dyes; bis-benzoxazolylthiophene (BBOT); and xanthene dyes;
fluorophores such as anti-stokes shift dyes which absorb in the
near infrared wavelength and emit in the visible wavelength, or the
like; luminescent dyes such as
5-amino-9-diethyliminobenzo(a)phenoxazonium perchlorate;
7-amino-4-methylcarbostyryl; 7-amino-4-methylcoumarin;
3-(2'-benzimidazolyl)-7-N,N-diethylaminocoumarin;
3-(2'-benzothiazolyl)-7-diethylaminocoumarin;
2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole;
2-(4-biphenyl)-6-phenylbenzoxazole-1,3;
2,5-Bis-(4-biphenylyl)-1,3,4-oxadiazole;
2,5-bis-(4-biphenylyl)-oxazole;
4,4'-bis-(2-butyloctyloxy)-p-quaterphenyl;
p-bis(o-methylstyryl)benzene; 5,9-diaminobenzo(a)phenoxazonium
perchlorate;
4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran;
1,1'-diethyl-2,2'-carbocyanine iodide; 3,3'-diethyl-4,4
',5,5'-dibenzothiatricarbocyanine iodide;
7-diethylamino-4-methylcoumarin;
7-diethylamino-4-trifluoromethylcoumarin;
2,2'-dimethyl-p-quaterphenyl; 2,2-dimethyl-p-terphenyl;
7-ethylamino-6-methyl-4-trifluoromethylcoumarin;
7-ethylamino-4-trifluoromethylcoumarin; nile red; rhodamine 700;
oxazine 750; rhodamine 800; IR 125; IR 144; IR 140; IR 132; IR 26;
IR5; diphenylhexatriene; diphenylbutadiene; tetraphenylbutadiene;
naphthalene; anthracene; 9,10-diphenylanthracene; pyrene; chrysene;
rubrene; coronene; phenanthrene or the like, or combinations
comprising at least one of the foregoing dyes. Dyes may be used in
amounts of about 0.001 to about 3.0 parts by weight, based on 100
parts by weight of the resin component.
Optical brighteners, which are substantially colorless,
fluorescent, organic compounds that absorb ultraviolet light and
emits it as visible blue light may also be present. Examples
include but are not limited to stilbenes such as derivatives of
4,4'-diaminostilbene-2,2'-disulfonic acid, bis benzoxazoyl
thiophenes, for example UVITEX OB from Ciba Geigy,
2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene, oxazinones such as
CARTAX CXDP form Clairant, coumarin derivatives such as
4-methyl-7-diethylaminocoumarin, 1,4-bis(O-cyanostyryl) benzol, and
2-amino-4-methylphenol. Optical brighteners may be used in amounts
of about 0.001 to about 3.0 parts by weight, based on 100 parts by
weight of the resin component.
Suitable flame retardants may be organic compounds that include
perfluoroalkyl groups, phosphorus, bromine, and/or chlorine.
Non-brominated and non-chlorinated flame retardants may be
preferred in certain applications for regulatory reasons. When
present, phosphorus-containing flame retardants may be present in
amounts of about 1.0 to about 20 parts by weight based on 100 parts
by weight of the resin component.
Various salts may be used as flame retardants, for example
sulfonate salts such as potassium perfluorobutane sulfonate (Rimar
salt) and potassium diphenylsulfone sulfonate, as well as the
perfluoroalkane sulfonates described in U.S. Pat. No. 3,775,367 or
the like; or alkali metal or alkaline earth metal (such as lithium,
sodium, potassium, magnesium, calcium and barium) salts such as
Na.sub.2CO.sub.3, K.sub.2CO.sub.3, MgCO.sub.3, CaCO.sub.3, and
BaCO.sub.3, Li.sub.3AlF.sub.6, BaSiF.sub.6, KBF.sub.4,
K.sub.3AlF.sub.6, KAlF.sub.4, K.sub.2SiF.sub.6, Na.sub.3AlF.sub.6,
or the like. When present, such flame retardant salts may be used
in amounts of about 0.001 to about 1.0 parts by weight, more
specifically about 0.1 to about 0.5 parts by weight, based on 100
parts by weight of the resin component.
Shaped, formed, or molded articles comprising the polycarbonate
compositions are also provided. The polycarbonate compositions may
be molded into useful shaped articles by a variety of means such as
injection molding, extrusion, rotational molding, blow molding and
thermoforming to form articles such as, for example, computer and
business machine housings such as housings for monitors, handheld
electronic device housings such as housings for cell phones,
electrical connectors, and components of lighting fixtures,
ornaments, home appliances, roofs, greenhouses, sun rooms, swimming
pool enclosures, and the like. In addition, the polycarbonate
compositions may be used for such application as backlit displays
and other devices such as organic light emitting diodes,
advertising displays, score boards, business equipment displays,
electronic game displays, medical device displays, and
telephones.
The polycarbonate compositions are generally transparent, that is,
they have low haze and high transmission. As is known in the art,
obtaining transparent compositions is difficult, as many known
additives significantly adversely affect transparency. The percent
haze of a composition may be determined in accordance with ASTM
D1003, and calculated using formula (i):
.times..times..times..times..times..times..times..times..times..times.
##EQU00001##
In formula (i) the total transmission is the integrated
transmission and the total diffuse transmission is the light
transmission that is scattered by the film. The polycarbonate
composition has a percent haze of less than about 20%, specifically
less than about 15%, more specifically than about 10%, wherein the
percentages are calculated as indicated above. Outside of these
ranges of haze the polycarbonate may not be sufficiently
transparent.
In addition, the polycarbonate composition has a percent total
light transmittance of greater than about 70%, specifically greater
than about 80%, and more specifically greater than about 88%.
Percent transmission (% T) may be measured as per ASTM D1003 on 3.2
mm injection molded parts. Outside of these ranges of haze and
transmission the polycarbonate may not be sufficiently transparent.
In one embodiment a haze of less than about 20% and a percent
transmission of greater than about 80% are maintained at a useful
temperature range, i.e., generally about 0.degree. C. to about
100.degree. C., specifically about 0.degree. C. to about 80.degree.
C., or about 20.degree. C. about 70.degree. C.
Optionally, in addition to transparency, the polycarbonate
composition may have a yellowness index of less than about 10,
specifically less than about 5. Yellowness index (YI) may be
measured on 3.2 mm injection molded chips as per ASTM method
D1925.
The coefficient of thermal expansion (CTE) is the fractional
increase in length per unit rise in temperature. The exact
definition varies in the art depending on whether it is specified
at a precise temperature (true coefficient of thermal expansion) or
over a temperature range (mean coefficient of thermal expansion).
The mean coefficient of thermal expansion is used in this
disclosure. The temperature range used for the mean coefficient of
thermal expansion is 20.degree. C. to 70.degree. C. In general the
CTE can vary from about 20 to about 70 um/m/.degree. C. In some
instances it may be from about 15 to about 40 um/m/.degree. C. CTE
may be measured on films or on molded parts as described in ASTM
E831.
It is believed that adjustment of the CTE of the thermoplastic
resin component leads to the decreased waviness of the flat films.
Films, particularly light diffusing films may be tested to evaluate
their robustness to conditions of elevated temperatures and
elevated levels of relative humidity. For example, a film having a
nominal thickness of 140 micrometers is produced and cut into
several rectangular pieces suitable for use in a 15 inch (about 38
centimeter) backlight module. Two such cut films are each placed on
a glass plate having a larger width and length than the film. The
maximum height of the bottom of any edge of the film above the
glass plate (i.e., deviation from flatness) was measured as 0.00
inches, using a rule having a 1/100-inch (0.254 mm) scale. Each
film is then taped to the glass plate at three edges (the two short
edges and one of the long edges). One of these (Set A) is placed in
a chamber where the temperature is maintained at 65.degree. C. and
relative humidity at 95% for a period of 500 hours. The other (Set
B) is subjected to a thermal cycling test, by being placed in a
chamber where the temperature was cycled between 85.degree. C. and
-35.degree. C. (minimal moisture content in the air, e.g., less
than or equal to about 60% relative humidity), with the temperature
held at each extreme for 1 hour and then changed to the other
extreme at a rate of 20.degree. C. per minute. 100 such cycles are
run.
After completion of each test, the set is removed from the chamber
and placed at 22.degree. C., 50% relative humidity for 14 days. The
tapes are removed from the edges of the film and the maximum
deviation from flatness at any edge is measured. In accordance with
this test, the films disclosed herein are capable of having a
maximum deviation from flatness, as measured at an edge when placed
on a glass plate of less than or equal to about 0.1 inches (about
0.3 centimeters), more specifically less than or equal to about
0.05 inches (about 0.1 centimeter), even more specifically less
than or equal to about 0.02 inches (about 0.05 centimeter). The
glass filled light-diffusing films are also capable of having a
maximum deviation from flatness, as measured after a high heat,
high humidity or thermal cycling test as described above of less
than 0.1 inches (about 0.3 centimeters), more specifically less
than 0.05 inches (about 0.1 centimeter), even more specifically
less than 0.03 inches (about 0.08 centimeter). Furthermore, the
glass filled light-diffusing film has an average defect size of
less than or equal to about 0.2 millimeters, wherein the average
defect is a numerical average of a major diameter of the defect and
a minor diameter of the defect.
In addition to the foregoing combination of excellent optical
properties and improved flatness, the polycarbonate compositions
may additionally have good physical and mechanical properties.
One particularly advantageous property is melt stability, which as
used herein is the resistance to molecular weight degradation of
the polymer as reflected by the weight average molecular weight. In
addition to a low coefficient of thermal expansion, as described
above, the polycarbonate composition may have an improved melt
stability at high temperatures, e.g., about 250.degree. C. to about
350.degree. C. Melt stability may be measured using a melt
viscosity index according to ASTM D1238 wherein the melt viscosity
over a 18 minute period (cm.sup.3/10 min) at 300.degree. C. is
compared to the melt viscosity measured over a 6 minute time span
under the same conditions. Retention of at least about 70% of the
initial, 6 minute, melt viscosity value after 18 minutes at
300.degree. C. is preferred. The polycarbonate compositions may
have a melt viscosity index at 300.degree. C. of generally about
0.5 to about 30 cm.sup.3/10 min, or about 1.0 to about 20.0
cm.sup.3/10 min or further about 5.0 to about 15.0 cm.sup.3/10 min.
Outside these ranges of melt stability the polycarbonate may be
difficult to process into film or have poor mechanical properties.
Polycarbonate compositions with superior melt stability will show
retention of at least about 70% of their initial melt viscosity
after heating for about 18 minutes at 300.degree. C. Alternatively,
compositions with sufficient melt stability may have a molecular
weight degradation, after thermal processing at 300.degree. C. for
18 minutes, of less than about 30%, specifically less than about
25%, and more specifically less than about 15% of the initial
weight average molecular weight of the polycarbonate.
In addition, the polycarbonate compositions may have a melt volume
ratio (MVR) of about 0.5 to about 30, more specifically about 1.0
to about 20 cm.sup.3/10 minutes, measured at 300.degree. C. in
accordance with ASTM D1238.
The polycarbonate compositions may further have a heat deflection
temperature (HDT) of about 120 to about 170.degree. C., or about
130 to about 150.degree. C., measured at 0.45 Mpa on 3.2 mm bars r
according to ASTM D 648.
The polycarbonate compositions may further have a Notched Izod
Impact (NII) of about 50 to about 200 Joules per meter (J/m),
specifically about 100 to about 150 J/m measured at 23.degree. C.
using 3.2 mm bars in accordance with ASTM D256.
The flexural modulus of the polycarbonate composition may generally
be about 2500 to about 10000 MPa, measured at 23.degree. C. using
3.2 mm bars in accordance with ASTM D790. The filled polycarbonate
compositions may be used to form films, specifically a film of
optical quality, and more specifically a flat film of optical
quality. Such films are useful as diffuser films.
The films may be formed by processes such as film and sheet
extrusion, injection molding, gas-assist injection molding,
extrusion molding, compression molding, blow molding, and
combinations comprising at least one of the foregoing processes.
Film and sheet extrusion processes may include and are not limited
to melt casting, blown film extrusion and calendaring. Co-extrusion
and lamination processes may be used to form composition
multi-layer films or sheets. Single or multiple layers of coatings
may further be applied to the single or multi-layer substrates to
impart additional properties such as scratch resistance, ultra
violet light resistance, aesthetic appeal, and the like. Coatings
may be applied through standard application techniques such as
rolling, spraying, dipping, brushing, flow coating, or combinations
comprising at least one of the foregoing application techniques.
The disclosed film and sheets may alternatively be prepared by
casting a solution or suspension of the composition in a suitable
solvent onto a substrate, belt or roll followed by removal of the
solvent.
Oriented glass filled PC films may be prepared through blown film
extrusion or by stretching cast or calendared films in the vicinity
of the thermal deformation temperature using standard stretching
techniques. For instance, a radial stretching pantograph may be
employed for multi-axial simultaneous stretching; an x-y direction
stretching pantograph may be used to simultaneously or sequentially
stretch in the planar x-y directions. Equipment with sequential
uniaxial stretching sections may also be used to achieve uniaxial
and biaxial stretching, such as a machine equipped with a section
of differential speed rolls for stretching in the machine direction
and a tenter frame section for stretching in the transverse
direction.
In one embodiment, the thin films may have of a thickness of about
0.01 to about 3.0 millimeters (mm), specifically about 0.1 mm to
about 1.0 mm and more specifically 0.1 to 0.5 mm. The thin films
may be used in a backlit module display, more specifically a
backlit module display that provides a reduced amount of waving.
Reduced waving in polycarbonate films is obtained through a
decrease in the coefficient of thermal expansion. In one
embodiment, the coefficient of thermal expansion of the filled
polycarbonate films is reduced up to about 70% over films without
the glass. Other devices that may use the filled polycarbonate
compositions include for example, liquid crystal TV screens and
computer displays as well as flexible substrates for organic light
emitting diode applications.
The filled polycarbonate compositions may also be used to form a
multiwall sheet comprising a first sheet having a first side and a
second side, wherein the first sheet comprises a thermoplastic
polymer, and wherein the first side of the first sheet is disposed
upon a first side of a plurality of ribs; and a second sheet having
a first side and a second side, wherein the second sheet comprises
a thermoplastic polymer, wherein the first side of the second sheet
is disposed upon a second side of the plurality of ribs, and where
the first side of the plurality of ribs is opposed to the second
side of the plurality of ribs. The multiwall sheet is configured to
not impede the desired physical properties of the article.
The films and sheets described above are further thermoplastically
processed into shaped articles via forming and molding processes
including but not limited to thermoforming, vacuum forming,
pressure forming, injection molding and compression molding.
Multi-layered shaped articles may be formed by injection molding a
thermoplastic resin onto a single or multi-layer film or sheet
substrate by first providing a single or multi-layer thermoplastic
substrate having optionally one or more colors on the surface, for
instance, using screen printing or a transfer dye; conforming the
substrate to a mold configuration such as by forming and trimming a
substrate into a three dimensional shape and fitting the substrate
into a mold having a surface which matches the three dimensional
shape of the substrate; then injecting a thermoplastic resin into
the mold cavity behind the substrate to (i) produce a one-piece
permanently bonded three-dimensional product or (ii) transfer a
pattern or aesthetic effect from a printed substrate to the
injected resin and remove the printed substrate, thus imparting the
aesthetic effect to the molded resin.
Those skilled in the art will also appreciate that common curing
and surface modification processes including and not limited to
heat-setting, texturing, embossing, corona treatment, flame
treatment, plasma treatment and vacuum deposition may further be
applied to the above articles to alter surface appearances and
impart additional functionalities to the articles.
Some additional advantages of using the filled polycarbonate
compositions described above over polycarbonate without refractive
index matching glass may be that the opacity of the filled
polycarbonate composition to UV light improves UV resistance;
and/or that the glass increases the modulus, the heat distortion
temperature, the flame resistance, the chemical resistance, and/or
the scratch resistance of the thermoplastic resin component.
The following examples are merely illustrative and are not intended
to limit the scope of the disclosure in any way.
EXAMPLES
A typical process comprises dry blending the polycarbonate resin,
any additives, and the glass, compounding the same in a twin-screw
extruder and pelletizing, followed by film extrusion of the
pellets. Table 2 sets forth the general formulation of the dry
blend. The polycarbonate powder used was LEXAN.RTM. 105 from
General Electric, having a Mw of about 30,000 with a MVR at
300.degree. C. of about 7.0 cm.sup.3/10 min.
TABLE-US-00002 TABLE 2 Raw material Weight Percent Polycarbonate
powder 80 100 Mold release agent 0.145 Phosphite Stabilizer 0.095
Antistatic additive 0.750 Glass 0 20
The glasses used in the following examples are shown in Table 3. In
Table 3, "ARG" is a boron compound and alumina-free milled glass,
grade ARG from Nippon Electric Glass (NEG) Co., "ECR" is a
corrosion resistant fiber glass from the Fiberex Co., "DBC" is a
dense barium crown glass from Pilkington Co., and "E Glass" is
borosilicate glass fibers from either PPG Co. or NEG, or a milled
borosilicate glass from Owens Corning (OC) Co.
TABLE-US-00003 TABLE 3 Average Average post- Glass type, Grade
Refractive Diameter, processing form name Supplier index, n.sub.d
.mu.m aspect ratio ARG, milled GAP-50 NEG 1.594 13 4 fiber ECR,
503-K-275 Fiberex 1.576 13 13 chopped fiber DBC, DBC589 Pil- 1.589
4.2 1 powder kington E-chopped, Chop PPG 1.550 10 25 fiber Vantage
3540 E milled, 737 BC OC 1.550 14 4 fiber E chopped, T-511 NEG
1.550 13 60 fiber
The samples were prepared using a W-P 30 mm (1.18 inches) twin
screw extruder with an aspect ratio set at length/diameter of 29.
The barrel temperature was 480.degree. F. to 550.degree. F.
(249.degree. C. to 288.degree. C.) and the die temperature was
550.degree. F. (288.degree. C). The screw speed was set at 30 rpm
and the screw torque was set at 80%.
After being compounded and pelletized, the samples was extruded
into a film using a Killion single screw extruder with a Mega
Machinery calendaring line (single screw extruder, film die, and
calendaring roll stack) to extrude the resin batches into films
with a matte/polish or a polish/polish texture. The operating
conditions included a barrel zone temperature of 480.degree. F. to
590.degree. F. (249.degree. C. to 310.degree. C.); a die zone
temperature of 580.degree. F. to 590.degree. F. (304.degree. C. to
310.degree. C.); a screw speed of 30 rpm and a die width of 16
inches (406 mm). For production of the matte/polish texture, the
calendaring roll setup was as follows: Roll Position 1 used
textured (40 microinches (0.04 mil) Ra nominal) silicone rubber,
which was 0.375 inches (9.525 mm) thick; and, alternatively Roll
Position 2 used a polished chromed steel roll where the chrome roll
temperature was 210.degree. F. to 284.degree. F. (100.degree. C. to
140.degree. C.), the rubber roll temperature was 120.degree. F. to
140.degree. F. (49.degree. C. to 60.degree. C.), which produced a
film thickness of 0.005 to 0.012 inches (0.127 mm to 0.305 mm).
Alternatively, polished chrome steel rolls were used in both Roll 1
and Roll 2 positions to produce a polish/polish texture.
The samples were analyzed and it was found that use of glass
lowered the coefficient of thermal expansion. Glass loadings of 5
wt. % or higher and aspects ratios of 4 and higher were found to
result in significant coefficient of thermal expansion reduction,
which translated into a significant improvement in the waving
performance of the films in the backlit module set up, compared
with the current films made of straight polycarbonate.
FIG. 1 shows the decrease in coefficient of thermal expansion as
the glass loading of various glasses are added to polycarbonate.
The reduction in coefficient of thermal expansion is translated
into an improvement of waving performance of the composition films
in a 14-inch (355.6 mm) notebook backlit module setting as is shown
in FIG. 2, wherein the number of waves formed by the diffuser film
directly on top of the 14-inch backlit module (light guide pipe)
decreases as the glass loading of both milled and chopped glass
fibers increases. Table 4 shows the number of waves formed by the
top diffuser film visible through the LCD panel in a 15-inch (381
mm) notebook display using some of the glasses as described in
Table 3.
TABLE-US-00004 TABLE 4 Wt. % Glass in Polycarbonate Glass Type
Number of Waves 0 -- 4 2 Chop Vantage 3540 3 5 0 10 0 20 0 2 737 BC
5 5 0 10 0 20 0 5 DBC589 2 10 2 20 2 5 ARG 0 10 GAP-50 0 20 0
Table 4 shows that samples loaded with at least 5 wt. % glass with
an aspect ratio of 4 or more give the best improvement, with no
waving visible through the LCD panel.
FIGS. 3 and 4 show the haze and total transmission for
polish/polish films of 12 mils (305 micrometers) thickness. The
extruded films were compressed in a Greenerd Hydrolair Model CPA-50
press under a pressure of 2000 psi (13.8 MPa) at a temperature of
525.degree. F. (274.degree. C.). The extruded films were preheated
for 1 minute at 0 psi, and then compression molded for 1 minute at
2000 psi (13.8 MPa), and cooled for 1 minute at 2000 psi (13.8
MPa).
Measurements were taken using a BYK Gardner Haze-Gard Plus
instrument from BYK-Gardner. Haze values are significantly reduced
as the refractive index difference between polycarbonate and the
glass is brought to less than 0.01 (503-K-275, DBC589 and GAP-50).
The best results are obtained with the GAP-50 glass for which haze
remains below 5% even at loadings as high as 20%. The predicted and
measured percent haze is calculated as indicated above where total
transmission is the integrated transmission and the diffuse
transmission is the light transmission that is scattered by the
film as defined by ASTM D 1003.
The diffuser films characterized in Table 5 are reinforced with
three types of glasses, each with a different refractive index. E
chopped fiber (n.sub.d=1.550), ECR chopped fiber (n.sub.d=1.576)
and DBC powder (n.sub.d=1.589). The ECR chopped fiber shows no
decrease in luminance even at 20 wt. % loading when compared to
polycarbonate without glass. Comparing ECR chopped fiber and E
chopped fiber shows the importance of the refractive index in
maintaining high luminance. DBC powder is an exception due to the
fact that samples containing this glass showed discoloration
associated with polycarbonate degradation (35% decrease in
molecular weight of polycarbonate at 20 wt. % loading of DBC
powder). This also caused the drop in percent transmission in FIG.
4 for this glass.
Table 5 shows the ratio of luminance of various filled
polycarbonate films to the luminance of a commercially available
polycarbonate film that contains no glass.
TABLE-US-00005 TABLE 5 % Glass ARG DBC E (T511) ECR 5 100.7 99.57
98.25 101.63 10 95.3 96.25 96.88 102.06 20 -- 94.52 93.71
100.28
The ECR chopped fiber shows no decrease in luminance even at 20 wt.
% loading when compared to polycarbonate without glass. The DBC
powder samples showed discoloration associated with polycarbonate
degradation (35% decrease in molecular weight of polycarbonate at
20 wt. % loading of DBC powder). This also caused the drop in
percent transmission in FIG. 4 for this glass.
The film made from a polycarbonate composition containing alkali
resistant glass was assessed for suitability of use as a top
diffuser by placing it in a commercial liquid crystal display
(model LP121X04 (A2) manufactured by LG Philips) in place of the
pre-existing top diffuser film. The luminance at a zero degree view
angle (i.e., on-axis) was measured (with the liquid crystal panel
removed) using an Eldim EZ Contrast 160D instrument, and found to
be 100.7% of the value obtained when a commercial top diffuser,
DL4248 manufactured by GE Structured Products and described in U.S.
patent application Ser. No. 10/787,158, was used. Therefore, the
luminance was at least 90% of that measured for the commercial top
diffuser.
It was observed that use of the alkali resistant glass may result
in voids and/or bubbles in the pellets and on the films made the
filled polycarbonate compositions. Treatment of the glass with
DF1040, a hydroxyl-capped polydimethylhydrogen siloxane available
from General Electric Company prevented the formation of voids
and/or bubbles. Table 6 below shows the molecular weight and melt
volume rate results exhibited with the low amounts of DF1040
passivation on glass-protected polycarbonate. As shown in Table 6,
MVR values at 6 and 18 min (15.8 and 15.4 cm3/10 min, respectively)
for non-passivated glass filled PC (Example 2 7) is higher than the
all other batches prepared with DF1040 passivation. Significant
decomposition has happened even during the 6 minute heating period.
DF581 is a hydroxyl-capped polydimethylsiloxane having no silicon
hydride groups
TABLE-US-00006 TABLE 6 De- MVR at MVR at crease 6 min 18 min Ex.
Mol. in MW (cm.sup.3/10 min (cm.sup.3/10 min No. DF1040 DF581 Wt.
(%)** at 300.degree. C.) at 300.degree. C.) 1-1 2 0 27536 4.58 9.75
8.80 2-1 1 0 27754 3.83 9.99 10.74 2-2 0.5 0 28195 2.30 8.93 9.50
2-6 0.25 0 27949 3.16 10.3 9.21 2-4 0.125 0 28177 2.36 10.2 9.59
2-7 0 0 25693 10.97 15.8 15.38 1-6 2 1 27271 5.51 9.83 8.89 1-5 1 1
27905 3.31 8.94 9.05 2-5 0 1 27449 4.89 11.9 11.29 A** 0 0 28860 0
8.55 7.96 *Control **Sample A, polycarbonate with no glass
It may be seen from the above data that DF581 is not as effective
as DF1040 if used alone (Ex. 2-5). Ex. 2-5 it gave a relatively
higher MVR value of 11.9 cm.sup.3/10 minutes than the batches in
which DF1040 had been used alone (e.g., Ex. 2-1).
Table 7 shows haze and transmission values of passivated glass
filled polycarbonate film samples (9 wt. % glass in polycarbonate)
compared to non-passivated glass as a function of DF1040 percentage
on the glass.
TABLE-US-00007 TABLE 7 DF1040 Ratio of Haze to Ratio of
Transmission concentration on non-passivated to non-passivated
passivated glass glass filled sample glass filled (Wt. %)
(Haze1/Haze2) * 100 sample (T1/T2) * 100 1 105.46 96.55 0.5 103.56
98.88 0.250 101.06 99.09 0.125 100.52 100.27 0 100 100
A loss of transparency was noted when DF1040 was used in amounts of
2 wt. % or above, in that compounded pellets containing the
passivated glass were white and opaque color. However, when lower
amounts of DF1040 were used e.g., 1 to 0.125 wt. %, as shown in
Table 7, the change in haze and transmission were much less. Good
haze and transmission were obtained with 0.125 wt. % DF1040.
Passivation at this concentration gave only a 0.5% increase in haze
and a 0.27% change in transmission compared to non-passivated
glass. These results showed that DF1040 passivation of alkali
resistant glass is quite effective at lower concentrations (0.25
wt. % or less on a glass surface) to prevent the melt decomposition
of polycarbonate without losing the transparency of the films.
In order to evaluate the performance of the glass filled films
compared to current commercial top diffuser films, haze and
transmission of polycarbonate films were measured by putting the
filled films behind the commercial film so that the glass filled
film was faced toward the light source in a BYK Gardner machine.
Alkali resistant glass filled polycarbonate films were also
measured for haze and transmission as single films for a comparison
as is shown in Table 8. A refractive index matching liquid was used
to prevent any measurement error due to air spaces between the
films. Table 8 shows the Transmission (T) and Haze (H) comparison
of alkali resistant glass filled polycarbonate films with GE top
diffuser film as single and double film configurations.
TABLE-US-00008 TABLE 8 Glass filled Single film Single Glass filled
film/ film/Top (% trans- film Top diffuser film diffuser film
Example mission) (% haze) (% transmission (% haze) Commercial 90.97
38.4 90.97 38.4 top diffuser film PC/10% 88.00 15.50 86.7 45.9 ARG
Run No. 10 90.00 14.57 86.7 45.9 (PC/5% ARG) Run No 5 89.83 5.66
89.5 38.6 (PC/5% ARG)
The results as reported in Table 8 show that the ARG glass did not
affect the transmission and haze values to a great extent. It is
noted that top light-diffusing films, i.e., the light-diffusing
film nearest to the liquid crystal display, generally have a haze
value of less than or equal to 85%, more particularly a haze value
of less than or equal to 50%. Therefore, the change in haze and
transmission is small enough to not change the optical properties
of films in the LCD applications.
It should be noted that resin molecular weight (melt flow rate) and
therefore film process conditions play a role in the final
properties of the films. For example, as is shown in Table 8, run
number 5 is the lowest haze film (having a haze value of 5.7% and a
coefficient of thermal expansion of 62 ppm um/m/.degree. C.)
containing alkali resistant glass (5 wt. % glass in polycarbonate).
It was produced using high flow (lower molecular weight with a melt
flow index of 17.5 cm.sup.3/10 min) polycarbonate resin at low die
temperature (480.degree. F., 249.degree. C.) with chrome roll
temperatures of 280.degree. F. (138.degree. C.) and with a screw
rate of 20.0 rpm at a melt pressure of 950 psi. Similarly, run
number 10 is the standard polycarbonate resin (melt flow index of
7.5 cm.sup.3/10 min) that was produced at 480.degree. F.
(249.degree. C.) die temperatures with a lower roll temperature of
210.degree. F., (99.degree. C.) and at a higher screw rate of 60
rpm. The film produced at run number 10 had a lower coefficient of
thermal expansion but a relatively higher haze than run number 5.
(CTE: 48 um/m/.degree. C., single film haze 14.6%).
The singular forms "a," "an," and "the" include plural referents
unless the context clearly dictates otherwise. The endpoints of all
ranges directed to the same amount, property, or characteristic are
inclusive and independently combinable. All references are
incorporated herein by reference.
Although the disclosed compositions have been described with
reference to an exemplary embodiment, it will be understood by
those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without
departing from the scope of the disclosure. In addition, many
modifications may be made to adapt a particular situation or
material to the teachings of the disclosure without departing from
essential scope thereof. Therefore, it is intended that the
disclosure not be limited to the particular embodiment disclosed as
the best mode contemplated for carrying out this invention, but
that the disclosure will include all embodiments falling within the
scope of the appended claims.
* * * * *